This invention relates generally to insulated containers. More specifically, it relates to improvements in vacuum insulated containers.
To provide thermal insulation by the use of a substantial vacuum between the spaced side walls of a container is, of course, so well known as to require no extensive discussion. Generally, the prior art on this subject with which the applicants are familiar may be categorized according to the material from which the container is made.
First and most common, are those containers made of glass. Glass, while offering numerous advantages, has some disadvantages. Its greatest disadvantage is that it is subject to breakage both in the manufacturing process and in use. To minimize this problem the art has resorted to a number of devices. These include protection by a jacket of metal or plastic, means to adsorb shock and prevent movement of the glass in the jacket. Very frequently the thermos bottle is provided with a plastic liner to prevent glass from a broken filler from entering into a foodstuff held in the bottle. Another disadvantage of glass is its cost, which is relatively high percentage of the cost of the entire container.
Another commonly used material for vacuum insulated containers is metal, particularly stainless steel. Vacuum or thermos bottles have been made from relatively thick metallic material for some time (see, for example, U.S. Pat. No. 3,331,522 assigned to the present assignee). These bottles, while practically eliminating the breakage problem, are quite costly to manufacture and, therefore, are costly to the consumer.
While glass and metal vacuum bottles are those most widely used in the industry, we are aware that in the literature it has been proposed to use other materials such as ceramics, plastics or various laminated constructions. To our knowledge none of these alternative constructions have ever appeared as commercially acceptable products for each apparently has its own set of problems. Plastics and ceramics may be porous and subject to outgassing, i.e., the release of entrapped gases in the material, thus destroying the vacuum. Laminates are costly and usually involve the use of plastics and natural materials which themselves are unsatisfactory as stated above.
In the light of the foregoing it is believed that significant advantages can be achieved by the provision of a vacuum or thermos bottle which is substantially free of the problems of the prior art.
Therefore, it is an object of this invention to provide a novel vacuum insulated container which is not subject to breakage, but is relatively economical to manufacture.
It is another object of this invention to provide a novel vacuum bottle made out of commonly available materials which are impervious and not subject to any significant outgassing.
It is a still further object of this invention to provide a novel vacuum container which may be fabricated using well known material and manufacturing techniques whereby it may be made relatively economically.